POSIX 7 http://pubs.opengroup.org/onlinepubs/9699919799/utilities/tabs.html
Set the tab size displayed by the terminal.
The default is 8.
E.g.:
printf '1\t1\n12345678\n'
shows on the terminal as:
1 1
12345678
If you do:
tabs 4
then we see instead:
1 1
12345678
Tabs go up to multiples, so:
printf '1\t1\n12\t1\n12345678\n'
Shows as:
1 1
12 1
12345678